SATLASGravitational waves · Ground
KAGRA
OperatingOperating since April 2020.
A 3 km laser interferometerinterferometryCombining waves from separate receivers coherently. In radio and optical astronomy, correlating signals from separated telescopes gives the resolution of one as large as their separation. In gravitational-wave detection, a laser Michelson interferometer measures tiny differential changes in its arm lengths. underground in the Kamioka mine: the first large gravitational-wave detector built underground, where seismic noise is lower, and designed to run its sapphire test masses cryogenically, near 20 K, to cut thermal noise (they were at room temperature in its first joint run, in April 2020). It adds a fourth site to the LIGO–Virgo–KAGRA network for localisationsky localisationWhere on the sky a source probably lies, published as a HEALPix probability map; its size is quoted as the area containing 90% probability. Two detectors give long arcs of hundreds to thousands of deg²; a third and fourth detector shrink it by triangulation..
- Operator
- ICRR, KEK, NAOJ
- Site
- Kamioka, Japan
- Frequency band
- 10 Hz – 5 kHz
- Messenger
- Gravitational waves
- Joined observing (O3)
- April 2020
Frequency band
Gravitational-wave frequency, from pulsar timing arrays (nHz) through space interferometers (mHz) to ground-based detectors (kHz).
Sky coverage
A nearly omnidirectional antenna pattern, like all ground interferometers: it responds to most of the sky at once, with blind spots set by the orientation of its arms.
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Verified 15 November 2026.